Field of the Invention
The present invention is related to image encoding and decoding and more particularly, image encoding and decoding based on video coding.
Related Art
As multimedia environments are spreading widely, various types of terminals and networks are being introduced, and user requirements are being diversified accordingly.
In other words, as performance and computing capability differ among terminals, supported performance also varies depending on the type of terminal. For the case of networks through which information is transmitted, too, not only the physical structure such as a wired and wireless network but also the functions supported by networks are diversified according to the type of transmitted information, the amount of information, communication speed of information, and the like. A user selects a terminal and network to use depending on the function wanted by the user; also, terminals and a spectrum of networks provided by service providers to users are being diversified.
In this regard, HD (High Definition) resolution broadcasts are now being serviced not only for domestic regions but also for overseas regions, by which more and more people are being accustomed to high resolution, high quality images. For this reason, a plurality of image service-related organizations is working hard on developing next-generation image devices.
On the other hand, in addition to HDTVs, public attention to UHD (Ultra High Definition) TVs, which provide a resolution more than four times the resolution of HDTV, is increasing; thus, demand for a technology which can compress and process images of higher resolution and higher quality is getting higher.
To compress and process images, various technologies can be employed, including: inter-prediction technology estimating pixel values in a current picture by using the pictures located temporally before and/or after the current picture, intra-prediction technology estimating pixel values of a current picture by using pixel information of the current picture, and entropy coding technology assigning short code words to frequently appearing symbols but longer code words to those symbols appearing in low frequency.
As described above, by taking account of functions provided differently according to the types of terminals and networks and diversified user requirements, supported image quality, image size, and image frame need to be diversified accordingly.
As described above, due to heterogeneous communication networks and various types of terminals providing various functions, scalability, which refers to a feature supporting various levels of image quality, image resolution, image size, frame rate, and so on, is now becoming one of important specifications for video formats.
Therefore, to provide services requested by the users in various multimedia environments based on a highly efficient method for encoding videos, it is necessary to provide a scalability function which enables efficient video encoding and decoding with respect to time, space, and image quality.